For the crust, sift together the flour, powdered sugar and salt and cut the butter into chunks. Place in a food processor and process, adding the eggs at the end, until a dough has formed. Roll out the dough into a circle and fit into an 11-inch (29cm) removable bottom tart pan. Chill for at least half an hour. Preheat the oven to 350F/180C. Blind-bake the crust by lining it with baking parchment, filling it with baking beans and baking for about 15-20 minutes. Remove the beans and paper and continue to cook the case for a further 10 minutes or until it is a light golden color. Remove from the oven and leave to cool.

To make the caramel, pour the glucose syrup into a large saucepan and bring it to a boil. Gradually add the sugar, stir and continue to cook until the sugar has started to caramelize and turn golden brown. At the same time, in a separate saucepan, bring the cream and salt to a boil. Remove the caramel from the heat and very carefully add the cream - be careful as the mixture can rise rapidly in the pan. Stir carefully over a low heat with a wooden spoon until smooth. Remove from the heat, add the diced butter, and stir again until smooth. Pour into the cooled crust and refrigerate for 15 minutes.

To make the ganache, bring the cream and honey just to a boil and pour over the chopped chocolate. Let it sit for a minute or two then stir until everything is smooth. Add more honey if it is too bitter. Once the mixture has cooled a little add the butter and stir gently until the mixture is smooth. Pour in an even layer on top of the cooled caramel, return to the refrigerator, and chill for 4-6 hours before eating.

Notes: I discovered that rock salts vary considerably in their 'saltiness', so to avoid over-salting the caramel mixture I recommend starting with the smaller amount and adding more only after tasting. Also, I tested the recipe with whipping cream (as opposed to double cream) since many people do not have access to the latter and discovered that it results in a slightly more liquid caramel (which you can see oozing out the sides of the tart in the above photo!). If you don't have access to double cream (a very thick cream with 48% butterfat) and want your caramel more solid, I would recommend reducing the cream by maybe 3 tablespoons and substituting it with a couple tablespoons of additional butter.